The present invention relates to an electronic timepiece having a reset lever having a bush including a bearing portion for rotatably supporting a transmission wheel.
An explanation will be given as follows of structure and operation of a conventional analog electronic timepiece disclosed in Japanese Utility Model Publication No. 45995/1993. In reference to FIG. 10 and FIG. 11, a movement (machine body including a drive portion) 400 of a conventional analog electronic timepiece includes a main plate 402 constituting a board of the movement 400. A dial 404 (shown in FIG. 11 by imaginary lines) is attached to the movement 400. In the analog electronic timepiece, in both sides of the main plate 402, a side thereof having the dial 404 is referred to as xe2x80x9cback sidexe2x80x9d of the movement 400 and a side thereof opposed to the side having the dial 404 is referred to as xe2x80x9csurface sidexe2x80x9d of the movement 400. A train wheel integrated to xe2x80x9csurface sidexe2x80x9d of the movement 400 is referred to as xe2x80x9csurface train wheelxe2x80x9d and a train wheel integrated to xe2x80x9cback sidexe2x80x9d of the movement 400 is referred to as xe2x80x9cback train wheelxe2x80x9d. A winding stem 410 is integrated rotatably to a winding stem guide hole of the main plate 402. The movement 400 is provided with a switch spring (not illustrated) for determining a position of the winding stem 410 in a direction of a central axis line 410A. A clutch wheel 408 is arranged coaxially with the winding stem 410. When the winding stem 410 is disposed at 0 stage, that is, in a time display state, the clutch wheel 408 is constituted not to rotate even when the winding stem 410 is rotated. When the winding stem 410 is at 1 stage, the clutch wheel 408 is constituted to rotate by rotating the winding stem 410. On xe2x80x9csurface sidexe2x80x9d of the movement 400, an area on the left side of the central axis line 410A of the winding stem 410 (first area) and an area on the right side of the central axis line 410A of the winding stem 410 (second area) are defined.
On xe2x80x9csurface sidexe2x80x9d of the movement 400, there are arranged a battery 420, a circuit block (not illustrated), a step motor 428, a surface train wheel, a switch apparatus (not illustrated) and so on. The surface train wheel is rotated by rotating the step motor 428. IC (not illustrated) and a crystal oscillator 422 are attached to the circuit block. The battery 420 constitutes a power source of the analog electronic timepiece. The crystal oscillator 422 constitutes an oscillation source of the analog electronic timepiece and is oscillated at, for example, 32,768 Hertz. The surface train wheel is rotatably supported by the main plate 402 and a train wheel bridge 412. On xe2x80x9csurface sidexe2x80x9d of the movement 400, the battery 420 is arranged at the area (first area) on the left side of the central axis line 410A of the winding stem 410 and the crystal oscillator 422 is arranged at the area (first area) on the left side of the central axis line 410A of the winding stem 410.
The step motor 428 includes a coil block 430, a stator 432, and a rotor 434. The coil block 430 magnetizes the stator 432 to rotate the rotor 434 when the coil block 430 is inputted with a motor drive signal outputted by IC. The rotor 434 is constituted to rotate by, for example, 180 degrees per second. On xe2x80x9csurface sidexe2x80x9d of the movement 400, a wire winding portion of the coil block 430 is arranged at the area (second area) on the right side of the central axis line 410A of the winding stem 410 and the rotor 434 is arranged at the area (second area) on the right side of the central axis line 410A of the winding stem 410.
A second wheel and pinion 442 is constituted to rotate via rotation of a fifth wheel and train 440 based on rotation of the rotor 434. The second wheel and pinion 442 includes a second wheel 442b, a second pinion 442c, a second upper shaft portion 442f and an abacus bead portion 442g. The second wheel and pinion 442 is constituted to rotate by one rotation per minute. A second hand 444 is attached to the second wheel and pinion 442. The rotational center of the second wheel and pinion 442 is arranged at the center of the main plate 402.
A third wheel and pinion 450 is constituted to rotate based on rotation of the second wheel and train 442. The third wheel and pinion 450 includes a third gear 450b, a third pinion 450c, a third upper shaft portion 450f and a third lower shaft portion 450g. A center wheel and pinion 452 is constituted to rotate based on rotation of the third wheel and pinion 450. The center wheel and pinion 452 includes a center wheel 452b, a center pinion 452c and a center core 452d. A minute hand 464 is attached to the center wheel and pinion 452. The center wheel and pinion 452 is constituted to rotate by one rotation per hour. The third upper shaft portion 450f of the third wheel and pinion 450 and the second upper shaft portion 442f of the second wheel and train 442 are rotatably supported by the train wheel bridge 412. An outer peripheral portion of the center core 452d is rotatably supported by the main plate 402. The abacus bead portion 442g of the second wheel and pinion 442 is rotatably supported by a center hole of the center core 452.
A minute wheel 474 is constituted to rotate based on rotation of the center wheel and pinion 452. An hour wheel 460 is constituted to rotate based on rotation of the minute wheel 474. A center hole of the hour wheel 460 is rotatably supported by an hour wheel support portion 402b of the main plate 402. The hour wheel 460 is constituted to rotate by one rotation per 12 hours. An hour hand 466 is attached to the hour wheel 460.
A clutch plate 480 having a resetting function similar to the reset lever is rotatably arranged to a clutch plate pin 402c of the main plate 402. The clutch plate 480 includes a winding stem contact elastic portion 480a, a rigid portion 480b, a spring portion 480c and a reset operation portion 480f. A third lower bearing portion 480d for rotatably supporting the third lower shaft portion 450g of the third wheel and pinion 450, is provided at the rigid portion 480b. The main plate 402 is provided with a clutch plate positioning portion 402f for determining a position of the clutch plate 480 when the winding stem 410 is disposed at 0 stage. A reset pin 426 is attached to the main plate 402. The reset pinion 426 is constituted to conduct to a reset terminal of IC. It is constituted that when the clutch plate 480 is brought into contact with the reset pin 426, reset operation is carried out. On xe2x80x9csurface sidexe2x80x9d of the movement 400, the clutch plate 480 is arranged at the area (second area) on the right side of the central axis line 410A of the winding stem 410 except a front end portion of the winding stem contact elastic portion 480a. 
When the winding stem 410 is disposed at 0 stage, a front end of the winding stem 410 pushes the winding stem contact elastic portion 480a and the reset operation portion 480f is brought into contact with the clutch plate positioning portion 402f. Under the state, the third pinion 450c is constituted to be brought in mesh with the center wheel 452b. On xe2x80x9csurface sidexe2x80x9d of the movement 400, the reset pin 426, and the clutch plate positioning portion 402f are arranged at the area (second area) on the right side of the central axis line 410A of the winding stem 410.
In reference to FIG. 12, when the winding stem 410 is pulled to 1 stage, that is, in a time correcting state, the front end of the winding stem 410 leaves the winding stem contact elastic portion 480a, the clutch plate 480 is rotated by spring force of the spring portion 480c and the reset operation portion 480f is brought into contact with the reset pin 426. Under the state, the third pinion 450c is not brought in mesh with the center wheel 452b. When the winding stem 410 is rotated under the state, the clutch wheel 408 is rotated and the center wheel and pinion 452 and the hour wheel 460 are rotated via rotation of the minute wheel 474 in mesh with the clutch wheel 408. According to the structure, in resetting the hands by pulling the winding stem 410 to 1 stage, in a state of stopping the second hand 444, by rotating the winding stem 410, the minute hand 464 and the hour hand 466 can be rotated. It is constituted that when the reset operation portion 480f is brought into contact with the reset pin 426, IC does not output the motor drive signal.
Further, other structures of the conventional analog electronic timepiece having the clutch plate and the third wheel and pinion having the reset function are disclosed in Japanese Utility Model Laid-Open No. 49281/1983, Japanese Patent Laid-Open No. 173991/1988, Japanese Patent Laid-Open No. 227876/1998 and so on.
However, according to the conventional analog electronic timepiece disclosed in Japanese Utility Model Publication No. 45995/1993, a circular hole constituting a third lower bearing portion 402d of the third wheel and pinion 450 is formed directly at the clutch plate 480. Therefore, when the hands are reset by pulling the winding stem 410 to 1 stage, the third lower bearing portion 402d of the third wheel and pinion 450 is inclined to the circular hole of the clutch plate 480 and therefore, there is a concern of bending or impairing the third lower bearing portion 402d by the clutch plate 480. Further, when a difference between a dimension of an inner diameter of the circular hole of the clutch plate 480 and a dimension of an outer diameter of the third lower bearing portion 402d, is increased in order to avoid the concern of bending or impairing the third lower bearing portion 402d by the clutch plate 480, in an operational state in which the winding stem 410 is set to 0 stage, a position of the third lower bearing portion 402d of the third wheel and pinion 450 is not accurately positioned and therefore, there is a concern that a state in which the third pinion 450c and the center wheel 452b are brought in mesh with each other, becomes unstable.
Further, according to the conventional analog electronic timepiece disclosed in Japanese Utility Model Publication No. 45995/1993, on xe2x80x9csurface sidexe2x80x9d of the movement 400, the battery 420 and the crystal oscillator 422 are arranged at the area (first area) on the left side of the central axis line 410A of the winding stem 410 and the clutch plate 480, the reset pin 426 and the clutch plate positioning portion 402f are arranged at the area (second area) on the right side of the central axis line 410A of the winding stem 410 and therefore, it is difficult to reduce the size of the movement.
It is an object of the invention to provide an electronic timepiece, particularly, an analog electronic timepiece in which when a winding stem is pulled to 1 stage and hands are set, there is not a concern of bending a bearing portion of a train wheel by a reset lever and there is not a concern of impairing the bearing portion of the train wheel by the reset lever.
Further, it is other object of the invention to provide an electronic timepiece, particularly, an analog electronic timepiece in which a mesh state of a train wheel is stabilized in an operational state in which a winding stem is disposed at 0 stage.
The invention is constituted such that in an electronic timepiece including a main plate constituting a board, a train wheel rotated by operating a motor constituting a drive source and a winding stem for correcting time, the train wheel includes a transmission wheel having a transmission gear and a transmission pinion and rotated by operating the motor and an indicator wheel having an indicator gear and an indicator pinion and rotated by rotating the transmission wheel. The electronic timepiece further includes a reset lever constituted to be brought into contact with the winding stem when the electronic timepiece is set to a time display state and not to be brought into contact with the winding stem when the electronic timepiece is set to a time correcting state and provided rotatably to the main plate and having a spring portion and a reset pin constituted to reset the electronic timepiece when the reset lever is brought into contact with the reset pin. According to the electronic timepiece, a guide portion of a bush having a center hole is integrated to a bush integrating hole of the reset lever by providing a clearance in a diameter direction therebetween. Further, according to the electronic timepiece, a lower shaft portion of the transmission wheel is rotatably integrated to the center hole of the bush. For example, the transmission wheel is a third wheel and pinion and the indicator wheel is a center wheel and pinion for integrating a minute hand constituted to indicate xe2x80x9cminutexe2x80x9d.
Further, the electronic timepiece of the invention is characterized to be constituted such that when the electronic timepiece is set to the time display state, a portion of the bush is brought into contact with a bush positioning portion of the main plate, the transmission pinion is brought in mesh with the indictor gear and the indicator wheel is rotated by operating the motor via rotation of the transmission wheel and constituted such that when the electronic timepiece is set to a time correcting state, the reset lever is rotated by a spring force of the spring portion, a portion of the reset lever is brought into contact with the reset pin and the transmission wheel is not brought in mesh with the indictor gear
By the constitution, when the hands are set by pulling the winding stem to 1 stage, there can be eliminated a concern of bending a lower bearing portion of the transmission wheel by the reset lever and a concern of impairing the lower bearing portion of the transmission wheel by the reset lever. Further, by the constitution, a state of bringing the transmission wheel and the indictor wheel in mesh with each other can be stabilized in an operational state in which the winding stem is set to 0 stage.
According to the electronic timepiece of the invention, it is preferable that the bush further includes a flange portion and a front end shaft portion, the fixed frame is fitted to the front end shaft portion and an axial direction clearance is provided between the lower face of the reset lever and the upper face of the fixed frame.
Further, it is preferable that a guide portion diameter difference (DHxe2x88x92DB) which is a difference between an inner diameter dimension (DH) of the bush integrating hole of the reset lever and an outer diameter dimension (DB) of the guide portion of the bush, is constituted to be larger than a bearing portion diameter difference (DCxe2x88x92DJ) which is a difference between an inner diameter dimension (DC) of the center hole of the bush and an outer diameter dimension (DJ) of the lower shaft portion of the transmission wheel.
Further, according to the electronic timepiece, it is preferable to constitute such that when a dimension (TB) between a lower face of the flange portion of the bush and an upper face of the fixed frame is equal to or smaller than the inner diameter dimension (DH) of the bush integrating hole of the reset lever, the axial line direction clearance (TS) is larger than the guide portion diameter difference (DHxe2x88x92DB).
By the constitution, when the winding stem is pulled to 1 stage and hands are set, it can be ensured to incline the bush and therefore, there can firmly be eliminated the concern of bending the lower bearing portion of the transmission wheel by the reset lever and there can firmly be eliminated the concern of impairing the lower bearing portion of the transmission wheel by the reset lever.